In an inkjet head which includes a plurality of nozzles and forms a dot by ejecting ink from each nozzle, there is a demand for an amount of ink ejected from each nozzle to be uniform. However, there are cases where there is a disparity between amounts of ink ejected from a plurality of nozzles. In addition, there are cases where there is a disparity between an amount of ink ejected previously and an amount of ink ejected subsequently even from the same nozzle.
Although slight, if there is a disparity between amounts of ink ejected from the nozzles, density unevenness or color unevenness occurs in a part where a color is required to be uniform. In order to obtain a printing result in which unevenness is not viewed, each element of the nozzle related to dot formation is required to be considerably uniform. However, since very high processing accuracy is required for this, product costs increase.